[Ed-and bentley]

Bentley is nine months eats purina puppy dry food, this is the third time in four months with loose stool, no blood he's acting normal just loose stool. I took him to the vet the first time nothing wrong with him just a little fever is all they found tried beef and rice no help pure pumpkin only temporary help then back to being loose again how can I help my little buddy? I will take him to the vet again this week but I thought I would try to get any info I can. I will do anything for the little guy that I can! please help